The present invention relates to a three-phase combined type circuit breaker comprising interrupting units for three-phase AC current hermetically contained in a single housing, or, more in particularly to a novel operating device for such a circuit breaker.
Generally, a three-phase combined type circuit breaker is so constructed that the interrupting units for three phases contained in a common hermetic housing are operated by a single operating device. Such a circuit breaker is disclosed in, for example, U.S. Pat. No. 3,857,006, entitled "Gas Insulated Switching Apparatus."
In conventional circuit breakers of this type, the interrupting units for three phases are actuated together to switch off the three phases in the case of an abnormality, such as lightning against one of the three phases which can be restored within a short period of time. All the conventional three-phase combined type circuit breakers so far developed are of this type.